EP2743664A2 - Device for measuring engine torque in a cycle - Google Patents

Abstract

The device has a deformation and/or strain sensor that is integrated into a ratchet (30) of a free wheel mechanism (28). A drive torque and/or driving power determination circuit is connected to the sensor. The sensor includes a microelectromechanical microsystem that is integrated into the ratchet. A sensor is arranged for determining angular velocity of a hub (10). Another drive torque determination circuit is provided in a separate manner from the former drive torque determination circuit. Independent claims are also included for the following: (1) a cycle hub (2) a bicycle (3) a system for controlling a pedal-assist motor in a pedal vehicle.

Description

Field

The present invention relates to a device for measuring the engine torque and / or the driving power of a cycle wheel, and a cycle wheel hub equipped with such a device.

Presentation of the prior art

The measurement of the driving power of a bicycle wheel is of interest in many cases, for example to evaluate the performance of a cyclist during a training. The knowledge at all times of the motor power provided by the cyclist is likely to help cyclists to optimize their practice. It allows them to better manage their effort and pedaling, training or during a race.

The driving power provided by the cyclist can be obtained by multiplying the engine torque, transmitted by the cyclist to the driving wheel, by the angular speed of this wheel.

The publication W02011 / 066075 discloses a bicycle rear wheel hub comprising a device for measuring the driving torque exerted on the driving wheel of the bicycle.

summary

Thus, there is provided here a device for measuring the engine torque and / or the engine power developed on a hub body by a freewheel body connected to the hub body by a freewheel mechanism, the device comprising at least one sensor deformation and / or stress on or integrated with at least one pawl of said mechanism and a circuit connected to the sensor for determining the driving torque and / or the driving power.

According to one embodiment, the sensor comprises at least one strain gauge on said pawl.

According to one embodiment, at least two deformation and / or stress sensors are disposed on or integrated with said pawl.

According to one embodiment, the sensor comprises at least one electromechanical microsystem integrated in the pawl.

According to one embodiment, the mechanism comprises a plurality of pawls, the device comprising at least one deformation and / or strain sensor on or integrated with each pawl.

According to one embodiment, the device comprises a power supply system of said circuit and / or said sensor comprising at least one solar panel and an energy storage device.

According to one embodiment, the device further comprises a sensor for determining the angular velocity of the hub body.

According to one embodiment, the device comprises a first motor torque determining circuit and a second driving power determining circuit distinct from the first circuit.

According to one embodiment, the first circuit transmits data to the second circuit via a wireless link.

There is also provided a cycle hub comprising a free wheel body, a hub body, a ratchet free wheel mechanism, and a device, as defined above, for measuring the engine torque and / or the engine power developed. on the hub body by the freewheel body.

According to one embodiment, the sensor is located in a recess provided on the surface of the pawl.

There is also provided a bicycle equipped with a measuring device as defined above.

• un dispositif de mesure tel que défini précédemment ; et
• des moyens pour faire varier la puissance du moteur à la hausse lorsque la puissance fournie par un utilisateur diminue et à la baisse lorsque la puissance fournie par l'utilisateur augmente.

There is also provided a system for controlling a pedal assistance motor in a pedal vehicle, comprising:

• a measuring device as defined above; and
• means for varying the engine power up when the power supplied by a user decreases and decreases when the power supplied by the user increases.

There is also provided a bicycle equipped with a pedal assistance engine and a servo system of this motor as defined above.

Brief description of the drawings

• la figure 1 est une vue de côté d'un mode de réalisation d'un moyeu de roue motrice de bicyclette ;
• la figure 2 est une vue en perspective éclatée du moyeu de la figure 1 ;
• la figure 3 est une coupe de la figure 2 selon la ligne III-III ;
• les figures 4 et 5 sont respectivement une vue en perspective et une coupe de l'un des cliquets du mécanisme de roue libre du moyeu de la figure 1 ;
• la figure 6 représente, sous la forme d'un schémabloc, un mode de réalisation d'un dispositif de mesure de puissance ;
• la figure 7 représente, sous la forme d'un schémabloc, un mode de réalisation d'un dispositif de mesure de couple ;
• la figure 8 représente, de façon partielle et schématique, un mode de réalisation d'une partie du dispositif de la figure 7 ; et
• la figure 9 représente, de façon partielle et schématique, une bicyclette motorisée équipée d'un dispositif de mesure de puissance du type décrit en relation avec la figure 6.

These and other objects, features, and advantages will be set forth in detail in the following description of particular embodiments in a non-limitative manner with reference to the accompanying figures in which:

• the figure 1 is a side view of an embodiment of a bicycle drive wheel hub;
• the figure 2 is an exploded perspective view of the hub of the figure 1 ;
• the figure 3 is a section of the figure 2 along line III-III;
• the Figures 4 and 5 are respectively a perspective view and a section of one of the pawls of the free wheel mechanism of the hub of the figure 1 ;
• the figure 6 represents, in the form of a schemablock, an embodiment of a power measuring device;
• the figure 7 represents, in the form of a schemablock, an embodiment of a torque measuring device;
• the figure 8 represents, partially and schematically, an embodiment of a part of the device of the figure 7 ; and
• the figure 9 represents, partially and schematically, a motorized bicycle equipped with a power measuring device of the type described in connection with the figure 6 .

detailed description

For the sake of clarity, the same elements have been designated by the same references in the various figures and, in addition, the various figures are not drawn to scale. In addition, only the elements useful for understanding the present description have been shown and are described. In particular, the well-known elements of a bicycle, including the frame structure of the bicycle and the connection between the wheels and the frame are not described in detail. In the rest of the description, unless otherwise indicated, the terms "substantially", "about" and "of the order of" mean "to within 10%".

It is known to equip the hub with a cycle drive wheel, in particular a bicycle, a motorized bicycle, a tandem or a tricycle, with a device for measuring the engine torque supplied by the cyclist to drive the driving wheel in rotation. , in general the rear wheel of the cycle, in particular to determine the motive power provided by the cyclist.

In one of the exemplary embodiments described in the document W02011 / 066075 , the torque measuring device comprises a test body equipped with strain gauges and disposed in the casing of the rear wheel gears. A disadvantage of this device is that it requires the use a specific test body. This results in significant modifications of an existing hub to install the measuring device. In addition, a housing must be provided to receive the test body of the measuring device, which leads to increase the mass and size of the hub of the rear wheel. This can further degrade the visual appearance of the cycle.

Thus, an object of an embodiment is to overcome all or part of the disadvantages of cycle wheel hubs described above equipped with torque and / or power measuring devices.

Another object of an embodiment is that the device for measuring the engine torque and / or the driving power of a cycle drive wheel changes little the structure of the existing drive wheel hubs.

Another object of an embodiment is that the measuring device has a small footprint.

Another object of an embodiment is that the measuring device can easily be adapted to the existing cycle wheel hubs.

The Figures 1 to 3 represent an embodiment of a hub 5 of a driving wheel of a cycle, for example the rear wheel of a bicycle.

The hub 5 comprises a hub body 10 having a cylindrical opening 12 of axis D. The opening 12 is intended to receive a hollow shaft D axis, not shown, attached to the frame of the bicycle. The hub body 10 is rotatably mounted around this shaft. The hub body 10 comprises a cylindrical central portion 14 and two lateral cheeks or bulges 16 and 18 of diameter greater than the diameter of the central portion 14. The cheeks 16, 18 are provided to provide anchoring points to the spokes, not shown of the wheel, these spokes being further mounted on a rim.

At one of its ends, the hub body 10 comprises a nozzle 20 intended to receive a free wheel body 22. The bulge 18 is located between the middle portion 14 and the tip 20. The freewheel body 22 comprises a cylindrical and fluted outer surface 24 which is provided to receive a gear box, not shown, also called pinion cassette. The gearbox is engaged with the bicycle chain and is rotated when the cyclist actuates the pedal of the bicycle. The freewheel body 22 is traversed by an opening 26 of axis D. In operation, the nozzle 20 is disposed in the opening 26 and bearings, not shown, are interposed between the nozzle 20 and the wheel body free 22.

A unidirectional free wheel mechanism 28 provides the connection between the hub body 10 and the freewheel body 22. The freewheel mechanism 28 comprises at least one pawl 30, generally at least two pawls. According to the present embodiment, each pawl 30 is disposed in a housing 32 provided in the nozzle 20. The inner surface of the opening 26 of the nozzle 20 comprises notches or teeth 34 all around the mouthpiece opposite. As an alternative, each pawl may be arranged in a recess provided in the freewheel body 22 and the outer surface of the end piece 20 may comprise notches or teeth all around the end-piece opposite the ratchets. 30.

In figure 3 two slots 32 have been shown and only one pawl 30 has been shown in the housing 32 situated at the top of the figure, since another pawl, not shown, is mounted in operation in the housing 32 located at the bottom of the figure. . By way of example, each housing 32 comprises a flat bottom 36, two flat lateral walls 38, a flat rear wall 40 and two recesses 42, each depression 42 being situated between one of the side walls 38 and the rear wall 40.

The Figures 4 and 5 represent the ratchet 30 in more detail. The pawl 30 comprises an upper wall 44, a flat bottom wall 46, a rounded front wall 48 connecting the front edge of the upper wall 44 to the front edge of the lower wall 46, a flat rear wall 50 connecting the rear edge of the upper wall 44 to the rear edge of the bottom wall 46 and side walls 52 connecting the side edges of the top wall 44 to the side edges of the bottom wall 46. The ratchet 30 further comprises lugs 54 projecting on either side of the ratchet 30 from the side walls 52.

Each pawl 30 is pivotably mounted in the housing 32 about an axis parallel to the axis D extending substantially at the lugs 54. The pawls 30 are slaved to cooperate with the notches or teeth 34 provided on the internal surface of the opening 26 of the nozzle 20. Each pawl 30 is permanently held in abutment against the teeth 34 by a not shown elastic return means, for example a spring.

For example, the maximum thickness of the pawl 30 is about 3 mm, the distance between the front wall 48 and the rear wall 50 is about 10 mm and the distance between the side walls 52 is about 10 mm.

The pawls 30 selectively secure the bodies 10 and 22 when the cyclist exerts a force to rotate the freewheel body 22 by means of a pedal connected to the gear box by a chain. The freewheel body 22 then rotates the hub body 10. When the cyclist does not exert a drive force in rotation of the freewheel body 22, the pawls 30 do not prevent the rotation of the hub body 10 continues. The driving wheel of the bicycle can then rotate without the crankset being rotated.

In the present embodiment, the pawl 30 includes a recess 56 provided on the upper wall 44. For example, the recess 56 has a maximum depth of less than or equal to 0.8 mm. A force and / or deformation sensor 60 is disposed in the recess 56. By way of example, the sensor 60 is glued to the bottom of the recess 56 by a diaper glue 62, especially a cyanoacrylate glue. The remainder of the recess 56 may be filled by a filler material 64, for example an epoxy resin. The sensor 60 is connected by electrical conductors 66, for example electrical wires, to a processing circuit, not shown. An opening 68, which opens into the central opening 12 of the hub body, is provided along the wall 38 of the housing 32. The opening 68 allows the passage of the wires 66 in the central opening 12. An opening 70, which opens into the central opening 12 of the hub body, is provided in the middle portion 14 of the hub body 10 and makes it possible to pass wires from the central opening 12 towards the outside of the hub body 10.

As a variant, several force / strain sensors are provided on the upper wall 44 of the pawl 30. According to another variant, a force / strain sensor is also provided on the lower wall 46 of the pawl 30 and / or on the side walls 52. As a variant, at least one force / strain sensor is provided for at least two pawls, preferably for each pawl 30 of the freewheel mechanism 28.

According to one embodiment, the sensor 60 comprises a strain gauge. The strain gauge is adapted to reflect the deformation of the pawl in electrical resistance variation. Preferably, the strain gauge is arranged to detect a deformation of the pawl 30 in a longitudinal direction, that is to say substantially perpendicular to the rear wall 50. Alternatively, a plurality of strain gauges are disposed on the wall 44 in different orientations.

According to one embodiment, the sensor is made in part or totally integrated way to the pawl 30. It can then include an electromechanical microsystem or MEMS (acronym for Microelectromechanical System).

For example, the pawl 30 is made of a material such as an aluminum alloy or steel. These materials have a high yield strength. Of course, any other suitable material is suitable.

The figure 6 represents, in the form of a schemablock, an embodiment of a system 70 for measuring the motive power supplied by the cyclist.

• un circuit 72 (Torque Sensor) de mesure du couple moteur C_M d'entraînement de la roue motrice par le cycliste ;
• un circuit 74 (Speed Sensor) de mesure de la vitesse de rotation ω des roues de la bicyclette ;
• un circuit 76 (Power Sensor) de détermination de la puissance motrice P_M fournie par le cycliste, relié au circuit 72 par une liaison 73 et au circuit 74 par une liaison 75 ; et
• un système 78 (Output) de stockage de données et/ou d'affichage de données relié au circuit 76 par une liaison 79.

The system 70 comprises:

• a circuit 72 (Torque Sensor) for measuring the driving torque C _M driving the driving wheel by the cyclist;
• a circuit 74 (Speed Sensor) for measuring the rotational speed ω of the wheels of the bicycle;
• a power sensor circuit 76 for determining the driving power P _M supplied by the cyclist, connected to the circuit 72 by a link 73 and to the circuit 74 via a link 75; and
• a system 78 (Output) for storing data and / or displaying data connected to the circuit 76 via a link 79.

où L est la distance qui sépare le point d'application de la force F de l'axe D et A est un facteur correctif, qui peut varier de 0 à 1. Le facteur A traduit le fait que la direction de la force F mesurée par le capteur 60 peut ne pas être exactement perpendiculaire à la droite perpendiculaire à l'axe D et passant sensiblement par le point d'application de la force F, c'est-à-dire sensiblement au niveau de la paroi avant 48 du cliquet 30.The circuit 72 determines the motor torque C _M from the force F exerted by the free wheel body 22 on the pawl 30 when the freewheel body 22 rotates the hub body 10 and obtained from the measurement provided by the sensor 60. The torque C _M is defined by the following relation (1): $${\mathrm{VS}}_{\mathrm{M}}=2\mathrm{x\; A\; x\; F\; x\; L}$$

where L is the distance between the point of application of the force F of the axis D and A is a corrective factor, which can vary from 0 to 1. The factor A reflects the fact that the direction of the force F measured by the sensor 60 may not be exactly perpendicular to the line perpendicular to the axis D and substantially passing through the point of application of the force F, that is to say substantially at the front wall 48 of the ratchet 30.

Knowing the driving torque C _M , it is possible to calculate the driving power P _M developed by the cyclist and defined by the following relation (2): $${\mathrm{P}}_{\mathrm{M}}={\mathrm{VS}}_{\mathrm{M}}\mathrm{x\; \omega }$$

où S est la section droite du cliquet 30 au niveau du capteur 60 et E est le module d'Young du matériau constituant le cliquet 30.According to one embodiment, the sensor 60 is adapted to provide a signal representative of the deformation ε of the pawl 30. The force F is then obtained by the following relation (3): $$\mathrm{F}=\mathrm{S\; x\; E\; x\; \epsilon }$$

where S is the right section of the pawl 30 at the sensor 60 and E is the Young's modulus of the material constituting the pawl 30.

When the sensor 60 comprises a strain gauge, the relative variation of the resistance of the strain gauge 60 is proportional, to the gauge factor, to the variation in the relative length of the gauge, and thus also to the variation in relative length. the part of the pawl that supports the strain gauge. Advantageously, a gauge 60 is selected which has a high gage factor, to obtain a signal of greater amplitude and thus improve the sensitivity of the sensor 60.

The angular velocity sensor 74 detects the rotational speed ω of the rear or front wheel of the bicycle as is known in the art. By way of example, the angular speed sensor 74 may be a Reed-type cell adapted to measure the angular speed of the hub 5. The Reed cell detects each revolution of the hub around the shaft on which the hub is mounted. means of a magnet disposed in a notch in the shaft, which provides a measure of the angular velocity of the wheel.

The system 78 may include a display screen and / or a memory for storing data. The circuit 76 is then adapted to display the driving power P _M determined on the display screen and / or to store in the memory the driving power value P _M determined.

It is understood that the circuit 76 can determine additional data, in addition to the driving power P _M , from the engine torque C _M and / or the speed of rotation ω. For example, the circuit 76 can determine the speed of the bicycle, distance traveled and travel time as well as average values, such as average power, average speed, etc.

According to another embodiment, the circuits 72 and 76 are at least partially merged.

The link 73, the link 75 and / or the link 79 may be wired links or wireless links. For example, data transmission over wireless links implements wireless data exchange methods. This may be the method known as ANT or methods based on the IEEE 802.15.4 standard, including the communication protocol known as Zigbee, or the IEEE 802.15.1 standard, including the communication known as Bluetooth. By way of example, the wired links may comprise a rotating commutator in the case where signals must be transmitted between two parts that are mobile in rotation relative to one another.

The motor torque measuring circuit 72, the angular velocity sensor 74, the driving power determining circuit 76 and the system 78 may be arranged at different locations on the bicycle. For example, the torque measuring circuit 72 may be located at the hub 5 of the rear wheel, the drive power determining circuit 76 and the data display system 78 may be located on the handlebar of the bicycle and the speed sensor 74 can be located on the stays of the cycle, for the measurement of the speed of rotation of the rear wheel, or on the fork of the cycle, for the measurement of the speed of rotation of the front wheel .

The figure 7 represents, partially and schematically, an embodiment of the circuit 72 for measuring the engine torque C _M , in the case where the link 73 is a wireless link.

• le capteur 60 (Sensor) qui fournit un signal S_F ;
• un circuit 80 de mise en forme du signal S_F fournissant un signal analogique SA ;
• un circuit de traitement 82 recevant le signal analogique SA et fournissant un signal S_C représentatif du couple moteur C_M fourni par le cycliste pour entraîner en rotation la roue arrière ; et
• un circuit de transmission 84 adapté à mettre en forme le signal S_C pour sa transmission par une liaison sans fil.

The measuring circuit 72 comprises:

• the sensor 60 (Sensor) which provides a signal S _F ;
• a circuit 80 for shaping the signal S _F providing an analog signal SA;
• a processing circuit 82 receiving the analog signal SA and providing a signal S _C representative of the engine torque C _M provided by the cyclist for rotating the rear wheel; and
• a transmission circuit 84 adapted to shape the signal S _C for transmission by a wireless link.

In the case where the sensor 60 is a strain gauge, the shaping circuit 80 comprises a Wheatstone bridge 86 connected to the strain gauge 60. The Wheatstone bridge 86 provides a signal S _WH to a analog amplifier 88 which amplifies the signal S _WH measured by the bridge 86. The amplifier 88 supplies the analog signal SA to the processing circuit 82.

According to one variant, the sensor 60 is a force sensor adapted to measure the force applied by the freewheel body 22 to the pawl 30 when the freewheel body 22 is rotated by the cyclist. In this case, if the signal provided by the sensor 60 is directly representative of the force applied to the pawl 30, the Wheatstone bridge 86 may not be present.

The processing circuit 82 comprises an analog / digital converter 90 (A / D) which converts the analog signal SA into a digital signal S _D. The processing circuit 82 further comprises a module 92 (Processor) receiving the signal S _D and supplying a digital signal S ' _C representative of the engine torque C _M. The processing circuit 82 comprises, for example, a microcontroller executing software instructions, and a memory. It can also be an electronic circuit configured to determine the engine torque C _M.

The processing circuit 82 further comprises a module 94 (Interface) for shaping the signal S ' _C for the to transmit to the transmission circuit 84. By way of example, the module 94 is adapted to shape the digital signal S ' _C for transmission on a serial synchronous data bus or SPI (English signal for Serial Peripheral Interface).

The transmission circuit 84 may comprise a radiofrequency transmitter 96 (RF) connected to an antenna 98. By way of example, the values of the signal S _C supplied by the processing circuit 82 may be transmitted via the transmitter RF 96 at antenna 98 for a 2.4 GHz radio frequency transmission according to the ANT wireless communication protocol.

The power supply of the torque measuring circuit 72 is performed by a power supply circuit 100. By way of example, the supply circuit 100 comprises a storage module 102 (storage), for example a battery or a capacitor, photovoltaic panels 104 (PV) and a power management module 106 (Energy Unit) connected to the energy storage module 102 and the photovoltaic panels 104. The module 106 is adapted to provide a substantially constant voltage at the circuit 72 from the energy provided by the storage means 102 and / or photovoltaic panels 104. The energy management module 106 is further adapted to recharge the storage means 102 from the energy provided by the photovoltaic panels 104. The photovoltaic panels 104 are, for example, placed at the rim of the rear wheel and / or spokes of the rear wheel. Alternatively, the power supply circuit 100 may furthermore comprise another energy source, in addition to or instead of the photovoltaic panels 104. It is, for example, a recovery system for energy associated with the rear wheel.

By way of example, the circuits 80, 82, 84, 102 and 106 may be arranged in a housing located in or on the middle part 14 of the hub body 10.

When the circuits 72 and 76 are merged, the processing circuit 92 can, in addition, receive from the sensor of angular velocity 74 a signal representative of the angular speed of the wheels and may, in addition to the engine torque C _M, determine the engine power P _M.

When the cyclist pedal, in a motor movement, the ratchets rotate the freewheel body 22 in rotation with the hub body 10, and the hub body 10 is rotated about the axis D. The ratchet 30 is deformed and varies the resistance of the strain gauge 60, which enables the processing circuitry 92 to calculate the value of the engine torque C _M, based on the signal supplied by the Wheatstone bridge 86. the pawl 30 works essentially in compression when the freewheel body 22 drives the hub body 10 in rotation.

Preferably, in the absence of torque transmitted by the bicycle chain, the sensor 60 is not biased. It is only when a driving torque is transmitted that the sensor 60 is stressed in compression. Advantageously, when the rear wheel is freewheeling, all the elements of the device 72 are set to cancel the unbalance of the Wheatstone bridge in the absence of bias and to also cancel the imbalances of the entire amplification chain and signal processing. For example, the processing circuit 92 automatically detects the freewheel phases by studying the instantaneous variations of the torque. Indeed, during a pedaling cycle, the torque transmitted by the cyclist passes through two maximums, corresponding to the positions where the right and left crank cranks are substantially at an angle of 60 ° with the vertical, and two minimums, when the cranks are in the low position. The processing circuit 92 is adapted to detect these repeated variations of the engine torque C _M. When there is no more variation, the processing circuit 92 deduces that the bicycle is freewheeling. The processing circuit 72 can then control the adjustment of operating parameters of the elements of the device 72 (variable amplification gain, variable resistances, etc.) for setting the zero of the device 72.

The figure 8 represents an embodiment of the Wheatstone bridge 86. The Wheatstone bridge 86 comprises four nodes A, B, C and D. The strain gauge 60 is connected between the nodes A and B. A fixed resistance R1, for example 120 ohms, is connected between the nodes B and C. Adjustable resistors R2 and R3 are respectively connected between the nodes A and D and between the nodes C and D. The signal S _WH provided by the Wheatstone bridge corresponds to the voltage V _OUT between the nodes A and C. The voltage V _ALIM is a constant voltage applied between the nodes D and B.

Alternatively, when the pawl 30 is provided with two strain gages, the additional strain gage may be connected to the Wheatstone bridge in place of the resistance R2. According to another variant, when the pawl 30 is provided with four strain gauges, they can be mounted as a complete Wheatstone bridge. As the gauges are fixed on the same pawl, this makes the signal delivered by the gauges insensitive to temperature variations, because the Wheatstone bridge is thus self-compensated.

In order to limit the power consumption, it is preferable to feed the strain gauge 60 in a pulsed manner by feeding it only a few tens of microseconds at a sampling frequency greater than 40 Hz.

The device 70 for measuring torque has the advantage of being relatively compact and lightweight and effectively measures the drive torque C _M of the wheel.

The figure 9 schematically represents a bicycle 110 equipped with a power measuring device of the type described in connection with the figure 6 . In this example, the driving power determining circuit P _M and the display and / or storage system 78 are arranged at the handlebar 112. They are, for example, integrated with a display box of FIG. a speedometer. The circuit 74 of determination of the driving torque C _M is disposed at the hub 10 of the rear wheel 114 of the bicycle 110. There is shown schematically a wireless communication antenna 116 of the circuit 78.

According to one embodiment, the bicycle 110 further comprises, on the side of its rear wheel 114, an assistance engine 118 for pedaling, for example an electric motor. In this embodiment, the power measurement device can be used to optimize the use of the assistance engine. An antenna 120 provided on the motor side 118 may make it possible to establish communication between the motor and the circuit 76 of the power meter. The measurement of the power supplied by the cyclist can be used to control engine speed variations 118, upwards as the power supplied by the cyclist decreases, and downwards as the power supplied by the cyclist increases.

Particular embodiments have been described. It will be appreciated that those skilled in the art may combine various elements of these various embodiments and variants without demonstrating inventive step.

Claims (14)

Device (70; 72) for measuring engine torque and / or motive power developed on a hub body (10) by a free wheel body (22) connected to the hub body by a freewheel mechanism (28) , the device comprising at least one sensor (60) of deformation and / or stress on or integrated with at least one pawl (30) of said mechanism and a circuit (72), connected to the sensor, for determining the engine torque and / or of the motive power. Device according to claim 1, wherein the sensor (60) comprises at least one strain gauge on said pawl (30). Device according to claim 1 or 2, wherein at least two deformation and / or strain sensors (60) are arranged on or integrated with said pawl (30). Device according to any one of claims 1 to 3, wherein the sensor (60) comprises at least one integrated electromechanical microsystem ratchet (30). Device according to any one of claims 1 to 4, wherein the mechanism (28) comprises a plurality of pawls (30), the device comprising at least one sensor (60) for deformation and / or stress on or integrated with each pawl ( 30). Device according to any one of claims 1 to 5, comprising a system (100) for powering said circuit and / or said sensor comprising at least one solar panel (104) and an energy storage device (102). Apparatus according to any one of claims 1 to 6, further comprising a sensor (74) for determining the angular velocity of the hub body (10). Device according to any one of claims 1 to 7, comprising a first motor torque determining circuit (72) and a second motor circuit (76). determining the distinct motive power of the first circuit. Apparatus according to claim 8, wherein the first circuit (72) transmits data to the second circuit (76) over a wireless link (73). A cycle hub (5) comprising a freewheel body (22), a hub body (10), a freewheel mechanism (28) with ratchets (30), and a device for measuring the motor torque and / or the motive power developed on the hub body by the freewheel body according to any one of claims 1 to 9. Hub according to claim 10, wherein the sensor (30) is located in a recess (56) provided on the surface of the pawl (30). Bicycle (110) equipped with a measurement device (70; 72) according to any one of Claims 1 to 9. A servo system for a pedal assistance engine (118) in a pedal vehicle (110), comprising: a measuring device (70; 72) according to any one of claims 1 to 9; and means for varying the engine power up when the power supplied by a user decreases and decreases when the power supplied by the user increases. Bicycle (110) equipped with a pedal assistance engine (118) and a servo control system of the engine according to claim 13.

Images